Objective: Circular RNAs (circRNAs) are involved in regulating of carcinogenesis of various cancer cells. However, the function of circRNAs in colorectal cancer (CRC) has remained largely unknown. This study investigated the characteristic expression of circRNAs in CRC and adjacent normal tissues, analyzed the miRNAs related to candidate circRNAs, and studied the correlation between circRNAs with clinical data of CRC. Methods: Human CircRNA microarray has been applied to screen the expressions of circRNAs of the CRC tissues and adjacent normal tissues. Quantitative real-time polymerase chain reaction (qRT-PCR) verified the candidate circRNAs in CRC tissue and patients’ peripheral blood. The circRNA array data were analyzed by GeneSpring 13.0 (Agilent) software. The diseases, pathways and functional enrichment analysis of these genes were performed using the KEGG system. In addition, the circRNA-miRNA network was constructed based on the miRanda-3.3 software. Statistical analysis was performed with SPSS23.0, GraphPad Prism, and Sigmaplot software. Results: In total, 13,198 circRNAs were identified as distinct between CRC and adjacent normal tissues, including 6,697 upregulated and 6,501 downregulated genes. Based on scores, six of them were selected for further verification in CRC tissues and peripheral blood. The hsa_circ_0004585 expression was significantly upregulated both in CRC patients tissue and peripheral blood. Hsa_circ_0004585 was positively correlated with patient’s tumor size, indicating the function of hsa_circ_0004585 in CRC carcinogenesis and metastasis. Conclusion: Hsa_circ_0004585 could be a potential biomarker for diagnosis of CRC.

Background: To study the specific expression of circular RNA (circRNA) in breast cancer and adjacent normal tissues to identify differentially expressed circRNA in breast cancer patients. To study the correlation between circRNA and clinical data of breast cancer, and to evaluate its potential as a breast cancer biomarker. Methods: The differential expression of circRNAs between the breast cancer tissues and adjacent normal tissues was screened by Human CircRNA Microarray. Candidate circRNAs verified by qRT-PCR. CircRNA was analyzed by Agilent GeneSpring 13.0 software. SPSS23.0, GraphPad Prism, and Sigmaplot software were used for statistical analysis. Perform T test, one-way ANOVA, curve regression analysis and ROC curve analysis for evaluating the diagnostic value of circular RNA. Results: Among the 2021 differentially expressed circRNAs, 546 were up-regulated and 1475 were down-regulated in breast cancer tissues. The validation study demonstrated that six circRNAs were downregulated. Among them, hsa_circ_0104824 proved high correlation between breast cancer tissues and plasma samples in its expression and diagnostic value. Conclusion: Hsa_circ_0104824 may serve as a promising predictive biomarker and therapeutic target for patients with breast cancer.

Homoharringtonine (HHT), a natural alkaloid derived from the cephalotaxus, exhibited its anti-cancer effects in hematological malignancies clinically. However, its pesticide effects and mechanisms in treating solid tumors remain unclear. In this study, we found that HHT was capable of inhibiting tumor growth after 5-days treatment of breast cancer cells, MCF-7, in vivo. Furthemore, HHT also significantly inhibited the cancer cell growth and induced cell apoptosis in vitro. miRNA sequencing proved miR-18a-3p was noticeably downregulated in the cells after HHT treatment. Moreover, downregulating miR-18a-3p increased HHT-induced cell apoptosis; our data supported that HHT suppressed miR-18a-3p expression and inhibited tumorigenesis might via AKT-mTOR signaling pathway. In conclusion: our study proved that HHT suppressed breast cancer cell growth and promoted apoptosis mediated by regulating of the miR-18a-3p-AKT-mTOR signaling pathway, HHT may be a promising antitumor agent in breast cancer treatment.

Breast cancer (BC) is one of the commonly occurring malignancies in females worldwide. Despite significant advances in therapeutics, the mortality and morbidity of BC still lead to low survival and poor prognosis due to the drug resistance. There are certain chemotherapeutic, endocrine, and target medicines often used for BC patients, including anthracyclines, taxanes, docetaxel, cisplatin, and fluorouracil. The drug resistance mechanisms of these medicines are complicated and have not been fully elucidated. It was reported that non-coding RNAs (ncRNAs), such as micro RNAs (miRNA), long-chain non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) performed key roles in regulating tumor development and mediating therapy resistance. However, the mechanism of these ncRNAs in BC chemotherapeutic, endocrine, and targeted drug resistance was different. This review aims to reveal the mechanism and potential functions of ncRNAs in BC drug resistance and to highlight the ncRNAs as a novel target for achieving improved treatment outcomes for BC patients.